In occasione della Notte Europea dei Ricercatori 2025, l’INAF-Osservatorio Astrofisico di Catania ha organizzato varie attività per il pubblico che si svolgeranno il 26 settembre.
Fossil groups (FGs) were initially believed to represent the end stage of galaxy group evolution, characterised by a significant luminosity gap between their two brightest member galaxies which was seen as an indicator of their advanced age. In this picture, FGs were thought to undergo a long passive evolution in which their bright satellites gradually merged into the central galaxy, making them fossil relics of the ancient Universe. However, results from the Fossil Group Origins (FOGO) project suggest a paradigm shift: FGs are not necessarily old, but rather isolated systems whose location within the cosmic web primarily regulates their evolution. In this scenario, the magnitude gap arises at low redshift thanks to the infall of galaxies on radial orbits, which enhances the merging rate observed in FGs.
In this seminar, I will review the progress achieved over the last 15 years that led to this new interpretation. I will discuss the luminosity functions, substructures, cosmic web environment, and orbital distribution of FG galaxies, also highlighting the view of FGs as transitional systems. Numerical simulations will also be presented to support the observational evidence, reinforcing the idea that the magnitude gap is a relatively recent feature rather than the imprint of an early formation epoch.
Inspired by dramatic discoveries from the Jansky VLA, VLBA, and ALMA, a large collecting area radio interferometer that will open new discovery space from proto-planetary disks to distant galaxies is being designed by the U.S. National Radio Astronomy Observatory (NRAO) and the broad scientific and technical communities. The next-generation VLA (ngVLA), which was strongly endorsed by the Astro2020 Decadal Survey as an essential research facility whose construction should begin this decade, is envisaged as an interferometric array with ten times greater sensitivity and spatial resolution than the current VLA and ALMA, operating in the frequency range of 1.2 - 116 GHz. Replacing both the VLA and VLBA, the ngVLA will be optimized for observations in the spectral region between the superb performance of ALMA at mm and sub-mm wavelengths, and the future Phase I Square Kilometer Array (SKA-1) at decimeter-scale and longer wavelengths. As such, the ngVLA will uniquely tackle a broad range of outstanding scientific questions in modern astronomy by simultaneously delivering the capability to: unveil the formation of Solar System analogues on terrestrial scales; probe the initial conditions for planetary systems and life with astrochemistry; characterize the assembly, structure, and evolution of galaxies from the first billion years to the present; use pulsars in the Galactic center as fundamental tests of gravity; and understand the formation and evolution of stellar and supermassive blackholes in the era of multi-messenger astronomy. In this presentation, I will provide a project update and discuss the overall science case that led to the current technical design of the ngVLA.
Concorso pubblico, per titoli ed esame, ai fini del reclutamento di una unità di personale con il profilo di "Ricercatore", Terzo Livello Professionale, con contratto di lavoro a tempo determinato […]
In occasione della Notte della Luna 2025, vi invitiamo a partecipare all'iniziativa "Stregati dalla Luna", che si svolgerà sabato 4 ottobre presso il Museo Diocesano di Catania.
L'organizzazione è curata dall'Istituto Nazionale di Astrofisica (INAF), dal Comitato Italiano per il Controllo delle Affermazioni sulle Pseudoscienze (CICAP) e dal Gruppo Astrofili Catanesi (GAC).
Concorso pubblico, per titoli ed esame, ai fini del reclutamento di 17 unità di personale con il profilo di "Tecnologo", Terzo Livello Professionale, con contratto di lavoro a tempo determinato […]
NGC1647 is a poorly studied open cluster, with considerable discrepancies in age reported in previous works. To improve the precision of its characterization, we applied HDBSCAN clustering in astrometric space, complemented by radial-velocity filtering, and identified 271 high-confidence cluster members. I will show as isochrone fitting to extinction-corrected photometry can provide a preliminary cluster age range. From TESS and K2 time-series photometry, we identified 95 periodic variables, including nine p-mode pulsators. By fitting stellar evolutionary models to these p-mode pulsators, we derived "asteroseismic" cluster parameters, Age and Metallicity. The seismic metallicity is consistent with spectroscopic estimates, while the derived age exhibits significantly higher precision than traditional isochrone-based results. Moreover, we analyzed LAMOST spectra using the ROTFIT tool and performed SED fitting to determine cluster extinction and conduct gyrochronology studies. This combined approach provides a refined benchmark for the fundamental parameters of NGC1647.
Pubblica selezione per titoli e colloquio per il conferimento di n. 1 borsa di studio, della durata di 12 mesi, eventualmente rinnovabile, dal titolo “Studio di metodologie di Machine Learning e […]
The magnetic activity of low-mass stars, driven by the interplay of convection and rotation in their interiors, is fundamental to their evolution and significantly affects the search for habitable exoplanets. Magnetic activity manifests at the surface as "spots" (or active regions) that influence the circumstellar environment through energetic radiation and eruptive events (flares and coronal mass-ejections, collectively termed “space weather”). The Sun exhibits a well-known 11-year activity cycle where spot emergence drifts from mid to low latitudes. However, one puzzling feature of the solar dynamo is the repeated emergence of spots in close proximity, which leads to long-lived sources of magnetic activity known as active nests. Nesting is observed on other low-mass stars, suggesting it is an innate, universal feature of stellar dynamos. It is theorized that non-axisymmetries in the generation and storage of the magnetic field preference the emergence of spots at specific latitudes and longitudes, leading to nesting. This phenomenon has consequences for predicting space weather near Earth and understanding the secular evolution of exoplanetary atmospheres. Studies of solar active nests have been limited by our single viewpoint from Earth. But with ESA’s Solar Orbiter now monitoring the Sun's far-side for several months each year, multi-viewpoint observations provide a pathway to study the formation and evolution of active nests. So far we have identified an active nest in 2022 that was responsible for 50–70% of all solar flares across the entire solar surface over five months (a prolific flare factory). In addition, we saw a dramatic intensification of solar flare activity in 2024 following the collision of two active nests. These continuous, multi-viewpoint observations strengthen the connection between solar activity and the nesting observed on other low-mass stars, a link that will be further explored with ESA’s PLATO mission.
